Heat exchanger having a coil and a corrugated tube, cooling circuit, fuel circuit and vehicle comprising such a heat exchanger

ABSTRACT

A heat exchanger comprising a fluid transport tube shaped to form a coil, the tube being made of a thermoplastic material and comprising at least one corrugated segment. 
     Cooling circuit, fuel circuit and vehicle comprising such a heat exchanger.

The present invention relates to a heat exchanger suitable for use in particular in a fuel circuit. The invention also concerns a cooling circuit, a fuel circuit and a vehicle comprising such a heat exchanger.

BACKGROUND OF THE INVENTION

A fuel circuit, more particularly a diesel circuit, includes a return circuit connecting a member for delivering fuel to the injectors (e.g. a distributor rail) back to the tank for the purpose of returning diesel that has not been injected. The return circuit generally includes a heat exchanger that is arranged to lower the temperature of the diesel from about 125° C. at the distributor member to about 85° C., in particular for the purpose of making it possible to use a tank that is made of polyethylene, which is lighter than a tank made of metal and less expensive than a tank made of polyamide that is better at withstanding high temperatures.

The heat exchanger comprises a fuel transport tube that is shaped to form a coil that is positioned under the vehicle in order to be subjected to a flow of air of the kind generated by the vehicle moving. The tube used at present is a smooth metal tube. The cooling that is obtained is effective, but the use of metal makes the heat exchanger relatively heavy.

To obviate that drawback, proposals have been made to replace the metal constituting the tube that is shaped into a coil with a plastics material, and more particularly a polyamide.

The heat exchanger is thus indeed lighter in weight, but a drop in its cooling performance is observed.

OBJECT OF THE INVENTION

It would therefore be advantageous to have a heat exchanger combining the advantages of metal tube coolers with the advantages of thermoplastic material tube coolers.

SUMMARY OF THE INVENTION

To this end, the invention provides a heat exchanger comprising a fluid transport tube of thermoplastic material shaped to form a coil, the tube being made of a thermoplastic material and comprising at least one corrugated segment.

The presence of corrugations makes it possible to increase the heat exchange area between the tube and the surrounding air, and the corrugations disturb the flow of air by creating turbulence therein. These two phenomena encourage heat exchange between the fluid transported by the tube and the air surrounding the tube.

Preferably, the tube has at least one bend portion extending in a corrugated segment.

The disposition of the corrugated segment in the bend portion of the tube makes it possible to omit a stage of bending as is necessary with metal tubes or of high temperature forming as is necessary with smooth tubes made of thermoplastic material. The shape of the bend portion is maintained by means of members for fastening the tube to its support.

The invention also concerns a cooling circuit and a fuel circuit comprising a heat exchanger having at least one of the previous features.

Besides, the invention concerns a vehicle comprising a body and such a heat exchanger, wherein the heat exchanger is fixed on the outside of the bodywork.

Thus, the heat exchanger is submitted to the flow of air resulting from the vehicle movement. The corrugations disturb the flow of air encouraging feat exchange between the transported fluid and the air surrounding the heat exchanger.

Other characteristics and advantages of the invention appear on reading the following description of a particular and non-limiting embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the accompanying drawings, in which:

FIG. 1 is a fragmentary view of a heat exchanger in accordance with the invention;

FIG. 2 is a detail view of a tube used in making up the heat exchanger; and

FIG. 3 is a fragmentary longitudinal section view of the tube;

FIG. 4 is a schematic view of a vehicle fitted with a heat exchanger in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

The heat exchanger of the invention is for installing in a diesel return circuit, of which pipes are represented in chain-dotted lines and given reference 1 in FIG. 1, and for being secured under the bodywork 2 of a motor vehicle.

The heat exchanger in accordance with the invention comprises a tube given overall reference 10, made up of a succession of smooth segments 11 and of corrugated segments 12. The tube 10 is made of a thermoplastic material, in this case a polyamide, and more particularly a polyamide 12. Nevertheless, the tube could be made of other thermoplastic materials, in the form of single layers or of multiple layers.

The tube 10 is connected to the return circuit 1 by means of endpieces in the form of teats or Christmas-tree serrations; other connection techniques could naturally be envisaged.

The tube 10 is shaped to constitute a coil, so as to present bend portions 13. These bend portions are shaped in the corrugated portions 12. Fastener members 14, themselves known and for example of the type commonly referred to as clips, connect the smooth segments 11 to the bodywork 2 of the vehicle. The fastener members 14 serve firstly to hold the tube 10 to the bodywork 2, and secondly to keep the bend portions 13 in shape.

The length of the tube 10 and its coil shape (number of bend portions), and also its disposition on the vehicle, serve to adapt the heat exchange produced by the heat exchanger to the requirements of the application.

The corrugations could be of a shape other than that shown in the figures, for example they could be helical in shape or they could have a section that is substantially sinusoidal, triangular, squarewave-shaped,

Naturally, the invention is not limited to the embodiment described and variant embodiments could be applied thereto without going beyond the ambit of the invention as defined by the claims.

Optionally, it is possible for the tube that is shaped into coils to be fastened to a plate that serves simultaneously to perform the function of protecting the tube and of performing a deflector function for directing a flow of air against the tube, the tube then extending between the bodywork and the plate.

By way of example, the heat exchanger is for fastening under the body of a vehicle or to any other location in which the heat exchanger will be subjected to a flow of air.

It is also possible to envisage other applications, and in particular static applications, for heating or cooling purposes,.

The tube may be made up of one or more parts.

The invention is not limited to the fuel circuit but also concerns for example cooling circuit mounted on vehicles or other devices. The described circuit can thus be used as a cooling circuit for an other application. 

1. A heat exchanger comprising a fluid transport tube of thermoplastic material shaped to form a coil, wherein the tube comprises at least one corrugated segment.
 2. A heat exchanger according to claim 1, in which the tube includes at least one bend portion extending in a corrugated segment.
 3. A heat exchanger according to claim 1, in which the tube comprises a succession of corrugated segments and of smooth segments.
 4. A heat exchanger according to claim 3, in which fastener members for fastening the tube to a support are mounted on the smooth segments.
 5. Cooling circuit comprising pipes connected to a heat exchanger according to any of the previous claims.
 6. Fuel circuit comprising pipes connected to a heat exchanger according to any of claims 1 to
 4. 7. Vehicle comprising a bodywork and a heat exchanger according to any of claims 1 to 4, the heat exchanger being fixed on the outside of the bodywork.
 8. Vehicle according to claims 7, wherein the heat exchanger is mounted under the bodywork. 